This invention relates to an open-end friction spinning machine of the type having at least one spinning unit containing two friction rollers that are arranged next to one another to form a wedge-shaped yarn forming gap serving as the yarn forming zone and, in the area that is opposite the yarn forming zone, is covered by a housing side.
In the case of a machine for open-end friction spinning described in German Published Unexamined Application (DE-OS) No. 32 13 478, it is known to cover the area of the friction rollers that is opposite the yarn forming zone by a housing side. The purpose is to form a flow duct especially for the friction roller rotating out of the wedge-shaped gap so that the roller will further carry along single fibers carried out of the wedge-shaped gap and return them to the wedge-shaped gap. Since in the case of this machine, the suction draught produced within both rollers is aimed only at the area of the wedge-shaped gap, it is improbable that the fibers once carried out of the wedge-shaped gap would go the whole way around one or both rollers and return into the wedge-shaped gap. It can rather be expected that these fibers will deposit and adhere at an undefined point in the area between the housing side and the rollers. The danger then exists that these fibers and possibly other dirt may collect and are later pulled back into the yarn forming zone in an uncontrolled manner, especially during a piecing process, after which both suction devices of the rollers are switched off. The existence of such collections of fibers may result in an impairment of the piecing process and create thin or thick points. In addition, there is the danger that these collections may be wedged between the rollers or between the rollers and the housing sides which can result in damage to the drums and/or their bearings. The otherwise advantageous covering of the area of the rollers that is opposite the yarn forming zone can therefore result in practical difficulties.
The invention is based on the objective of developing an open-end friction spinning machine of the initially mentioned type in such a way that the advantages of a covering of the area opposite the yarn forming zone are achieved but that the danger of disturbances is, at the same time, eliminated.
This objective is achieved according to the invention by providing means that can be switched on periodically in order to produce an air flow/current between the housing side and the rollers.
This air flow, which is produced especially during an interruption of the spinning process can be selected in a simple manner according to preferred embodiments of the invention to be so strong that fibers or flying fibers or other dirt existing in this area are removed thereby. It is assumed that individual fibers that have "lost their way" during the normal spinning operation are not damaging so that a periodic cleaning of the area of the rollers is sufficient according to these preferred embodiments.
In a further development of the invention, it is provided that the, air flow producing means for producing the air flow between the housing side and the rollers are housed in a servicing apparatus that can be moved along the spinning machine and can be selectively applied to the individual spinning units. The means for producing the air current therefore do not have to be installed at each spinning unit. Thus manufacturing costs are reduced while it is ensured at the same time that the servicing operations carried out by the servicing apparatus are the same at each spinning unit. It is preferably provided in this case that the means for producing the air current are arranged at a servicing apparatus that carries out other functions and especially a piecing process after a yarn breakage. In this case, the cleaning of the area surrounding the rollers is then combined with a piecing process so that the original conditions are restored for the piecing.
In a further development of the invention, it is provided that the servicing apparatus is equipped with a pot-shaped screen that can be applied to the edges of the housing side within which the means for producing the air flow are arranged. This ensures that the fiber residues, or dirt or other substances detached at the respective spinning unit are removed effectively and are not deposited at another point of the spinning unit or of an adjacent spinning unit.
In the case of an advantageous embodiment of the invention, it is provided that a blowing nozzle can be applied to the gap between the edge of the housing side and a surface line of a roller and a suction nozzle can be applied to the gap between the edge of the housing side and a surface line of the other roller. As a result, a defined air flow can be achieved that flows evenly past both rollers.
In a further development of the invention, it is provided that the area of the wedge-shaped gap of the spinning unit serving as the yarn forming zone is equipped with a removable partial housing and that the servicing apparatus is equipped with means for removing the partial housing and with the means for producing the air flow. By means of this development it is ensured that the cleaning is carried out while the spinning unit is open, the essential parts being exposed by moving away the partial housing and thus being well accessible.
In a further development of the invention, it is provided that the servicing apparatus is equipped with an auxiliary drive that can be applied to the rollers of the spinning unit. It thus becomes possible to drive the rollers at an appropriate speed during the production of the air flow, if necessary, also in reversed rotational direction.
In a further development of the invention, it is provided that the servicing apparatus is equipped with at least one cleaning element that can be applied to the cover/shell surfaces of the rollers. In this way, it is possible to combine the cleaning of the surroundings of the rollers with a cleaning of the roller cover surfaces. Advantageously, a brush-type cleaning element is used according to especially preferred embodiments of the invention.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, embodiments constructed in accordance with the present invention.